Field of the Invention
The present invention relates to a vibration wave motor to be employed in an optical device or the like.
Description of the Related Art
Conventionally, there has been known technology, as this type of the vibration wave motor, for moving the vibrator and a friction member relatively by bringing the vibrator that causes (ultrasonic) vibration cyclically in frictional contact with a friction member. An example of this vibration wave motor that is configured in a linear motion type and is used for linear motion focus drive is disclosed in the Japanese Patent Application Laid-Open No. 2014-212682.
The prior art disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2014-212682 includes a pressing member for generating pressing force to bring the vibrator in frictional contact with a pressing force transmitting member that transmits the pressing force between the vibrator and the pressing member. The pressing force transmitting member is held rotatably in a predetermined direction so that equal pressing can be effected regardless of posture of the vibrator.
However, in the prior art disclosed in the Japanese Patent Application Laid-Open No. 2014-212682, there has been a concern that since a configuration is not sufficient to restrict pressing force by the pressing member in the pressing direction, a contact position between the pressing member and the pressing force transmitting member is shifted. If the contact portion is shifted, since uniform pressing to the vibrator cannot be effected, a new concern arises that a characteristic of the vibration wave motor is not stable.